The wavelength of light absorbed for the following complexes are in the order:
$I: [Co(NH_3)_6]^{3+}; II: [Co(H_2O)_6]^{3+}; III: [Co(CN)_6]^{3-}; IV: [Co(NH_3)_5(H_2O)]^{3+}; V: [CoF_6]^{3-}$

Identify the weak field ligand from the following.

For which of the following pairs of complexes is the crystal field splitting energy $\Delta_0$ for $II > \Delta_0$ for $I$?

$I$	$II$
$(a). [Cr(H_2O)_6]^{2+}$	$[Cr(H_2O)_6]^{3+}$
$(b). [Fe(H_2O)_6]^{3+}$	$[Fe(CN)_6]^{3-}$
$(c). [Fe(CN)_6]^{3-}$	$[Ru(CN)_6]^{3-}$
$(d). [NiF_6]^{4-}$	$[NiF_6]^{2-}$

The complex ion that will lose its crystal field stabilization energy upon oxidation of its metal to $+3$ state is

The Crystal Field Stabilisation Energy $(CFSE)$ for $[CoCl_{6}]^{4-}$ is $18000 \; cm^{-1}$. The $CFSE$ for $[CoCl_{4}]^{2-}$ will be $...... \ cm^{-1}$.

Given below are two statements:
Statement $I$: Presence of a large number of unpaired electrons in transition metal atoms results in higher enthalpies of their atomisation.
Statement $II$: $d_{xy} = d_{xz} = d_{yz} < d_{x^2-y^2} = d_{z^2}$ and $d_{x^2-y^2} < d_{xy} = d_{xz} = d_{yz}$ are the $d$-orbital splittings in $[Fe(H_2O)_6]^{3+}$ and $[Ni(Cl)_4]^{2-}$ complex ions respectively.
In the light of the above statements,choose the correct answer from the options given below: